Neoplasia USMLE Step 1 Practice Question
A 68-year-old man with a 20-year history of Crohn's disease presents with progressive weight loss and diarrhea. Vital signs show BP 128/76, HR 92, RR 18, Temp 37.2°C, SpO2 98%. Colonoscopy reveals a 3-cm ulcerated mass in the terminal ileum with adjacent high-grade dysplasia; no perforations noted. CT abdomen shows focal wall thickening without distant metastases. Histopathology demonstrates adenocarcinoma. Hemoglobin is 10.2 g/dL. Which pathogenic sequence best explains this malignancy development?
Answer choices
- AViral integration → oncogene activation → direct transformation
- BAberrant Wnt signaling → loss of APC → polyp formation → carcinoma
- CDietary carcinogens → direct DNA adduct formation → mutation
- DBacterial translocation → epithelial apoptosis → dysplasia → carcinoma
- EChronic inflammation → mucosal injury → dysplasia → carcinomaCorrect answer
- FFistula formation → bacterial overgrowth → intestinal metaplasia → carcinoma
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